This invention relates to X-ray cardiosvascular examination apparatus which can be used for general purpose X-ray examinations also.
An established procedure for examining the vascular system of organs such as the heart involves injecting a radiopaque dye into the blood vessels and fluoroscoping the organ of interest with a suitable X-ray image to optical image converting device such as an X-ray image intensifier. The dye outlines the heart and the associated vascular system which can then be observed while it is functioning for circulatory obstructions, aneurisms and other defects. As is well known, in an intensifier, the X-ray image impinges on a fluorescent screen which is the image input plane of the intensifier. The fluorescent image is converted into an electron image and then into a miniaturized bright optical image which may be viewed with a video camera or recorded with a cine camera or a spot film camera. The fluoroscopic image from the intensifier as viewed by the video camera is displayed on a video monitor. One of the problems with this procedure is that certain important blood vessels are often disposed with their axes perpendicular to the viewing plane, thus making defects difficult to observe. In other instances, blood vessels in the heart are superimposed or concealed by other vessels so it is difficult to distinguish them and to observe the defects in them.
Angulating the image intensifier and X-ray source jointly is one approach to viewing blood vessels in the heart perpendicular to the viewing plane rather than axially. Angulation also permits viewing between vessels that would otherwise be superimposed or obscured if they were other than parallel to the viewing plane.
Some prior apparatus for performing the specialized vascular procedures have an X-ray source arranged on one side of the patient and an image intensifier system on the other side with the source and system on a common mounting which causes the central X-ray beam to remain directed at the image plane for various angles at which viewing of the heart or blood vessels is desired. In some prior apparatus, the patient is supported for limited lengthwise turning and longitudinal angulation relative to the X-ray beam to provide for viewing the heart at various angles. In other designs, the X-ray source can be angulated longitudinally while the patient is supported for limited lengthwise rotation or no rotation at all.
Typically, in X-ray apparatus used heretofore for the purposes indicated, the X-ray source and imaging devices are supported on the ends of a U-shaped or a C-shaped arm which can approach the patient endwise or laterally. Angulation is achieved by rotating the C-arm about a laterally extending axis or the U-arm about a longitudinal axis and angulating the source and intensifier longitudinally. The problem with either of these designs is that the patient is supported on a table and the source and intensifier are in free space. A major disadvantage of this open construction is that shielding the operator from stray and secondary X-radiation is difficult, if not impossible.